Electrodeposition of Nanomodulated Ceramic Thin Films
- PDF / 1,779,911 Bytes
- 7 Pages / 420.48 x 639 pts Page_size
- 89 Downloads / 241 Views
ELECTRODEPOSITION OF NANOMODULATED CERAMIC THIN FILMS
Jay A. Switzer*, Michael J. Shane, and Richard J. Phillips, University of Pittsburgh, Department of Materials Science and Engineering, Pittsburgh, PA 15261. *Present Address, University of Missouri-Rolla, Department of Chemistry and Graduate Center for Materials Research, Rolla, MO 65401
ABSTRACT Electrochemistry can be used for the atomic-level architecture of ceramic materials. In this report, ceramic superlattices based on the Tl.PbbOfLTldPbeOf system were electrodeposited with individual layer thicknesses as thin as 3nm. The superlattices were deposited from a single aqueous solution at room temperature, and the layer thicknesses were galvanostatically controlled. Substitution of T12 03 into PbO2 appears to stabilize a face-centered cubic structure with an average lattice parameter of 0.536nm. The lattice parameters for the T1,bbO. mixed oxides vary by less than 0.3% when the PbIT1 ratio is varied from 0.84 to 7.3. Because the modulation wavelengths are of electron mean free path dimensions, this new class of degenerate semiconductor metal-oxide superlattices may show thickness-dependent quantum optical, electronic, or optoelectronic effects. INTRODUCTION We have recently demonstrated that it is possible to electrodeposit nanomodulated ceramic superlattices based on the Tl.PbbOJfl 4 Pb.Or system [1]. An idealized superlattice structure with square-wave modulation of composition and/or structure is shown below in Figure 1. The thicknesses of the A and B layers are not necessarily equal, as long as the structure is periodic.
B
LIZ
A
Substrate
Figure 1
Idealized superlattice structure with square-wave modulation of composition and/or structure.
Mat. Res. Soc. Symp. Proc. Vol. 180. ©1990 Materials Research Society
1054
The idea of electrochemically depositing nanomodulated superlattices is not new, but it has not been applied previously to the deposition of nonmetallic materials. Several research groups have shown that compositionally modulated metallic alloys can be electrochemically deposited from a single plating bath by cycling either the potential or current [2-5]. The interest in nanomodulated metallic systems stems from their enhanced mechanical and magnetic properties [3,6]. We have chosen the T1.PbbOIfhPb.Of system for our study for several reasons: (1) during our previous work on the electrochemical and photoelectrochemical deposition of thallium (III) oxide films we found that it was possible to deposit highly oriented films [7-9], (2) the deposition of PbO2 [10,11 ] and Pb8T15 O• [12,13] are well documented, (3) the anhydrous oxides deposit directly at room temperature and require no heat treatment, (4) there is a nearly isomorphous series of mixed thallium/lead oxides that should grow epitaxially, and (4) the device applications of these types of materials have not been studied previously. We expect that these materials will prove to have very interesting optical and electrical properties. The end members of the series, PbO2 and T120 3,
Data Loading...
